U.S. patent application number 17/325816 was filed with the patent office on 2021-12-23 for adaptive energy detection threshold medium access based on deployment and traffic type.
The applicant listed for this patent is QUALCOMM Incorporated. Invention is credited to Aleksandar Damnjanovic, Marco Papaleo, Maarten Menzo Wentink, Yisheng Xue.
Application Number | 20210400730 17/325816 |
Document ID | / |
Family ID | 1000005614136 |
Filed Date | 2021-12-23 |
United States Patent
Application |
20210400730 |
Kind Code |
A1 |
Damnjanovic; Aleksandar ; et
al. |
December 23, 2021 |
ADAPTIVE ENERGY DETECTION THRESHOLD MEDIUM ACCESS BASED ON
DEPLOYMENT AND TRAFFIC TYPE
Abstract
Adaptive energy detection (ED) threshold medium access is
discussed based on deployment and traffic type. The network nodes
sharing a shared communication network are configured with multiple
discrete ED thresholds or a range of ED values. As a transmitting
node prepares to attempt access to the shared communication
spectrum, it identifies an access trigger condition within the
network. Such a condition may include traffic type, deployment, or
access conditions. In response to detecting an access trigger
condition, the transmitting node may select an ED threshold
associated with the access trigger condition. Alternatively, upon
detection of the access trigger condition, the transmitting node
may implement a random ED threshold from the candidate range of ED
threshold values.
Inventors: |
Damnjanovic; Aleksandar;
(Del Mar, CA) ; Wentink; Maarten Menzo; (Nijmegen,
NL) ; Xue; Yisheng; (San Diego, CA) ; Papaleo;
Marco; (Bologna, IT) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
QUALCOMM Incorporated |
San Diego |
CA |
US |
|
|
Family ID: |
1000005614136 |
Appl. No.: |
17/325816 |
Filed: |
May 20, 2021 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
63042367 |
Jun 22, 2020 |
|
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H04W 74/008 20130101;
H04W 74/0858 20130101; H04W 74/0825 20130101 |
International
Class: |
H04W 74/08 20060101
H04W074/08; H04W 74/00 20060101 H04W074/00 |
Claims
1. A method of wireless communication, comprising: identifying, by
a transmitter node, information for transmission on a shared
communication channel; identifying, by the transmitter node, for an
access trigger condition associated with access of the transmitter
node to the shared communication channel; performing, by the
transmitter node, an energy detection (ED) procedure for access to
the shared communication channel according to an ED threshold of a
plurality of candidate ED thresholds corresponding to the access
trigger condition; and transmitting, by the transmitter node, the
information on the shared communication channel in response to
success of the ED procedure.
2. The method of claim 1, wherein the access trigger condition
includes one or more of: a traffic priority of the information; an
inability by the transmitter node to successfully access the shared
communication channel for at least a threshold period of time; a
threshold error rate detected by the transmitter node, wherein the
threshold error rate identifies errors that trigger modification of
a contention window size; and a deployment location, wherein the
deployment location indicates one of an indoor deployment or an
outdoor deployment.
3. The method of claim 1, wherein the plurality of candidate ED
thresholds includes one of: one or more discrete ED thresholds
including at least a standard ED threshold, a relaxed ED threshold,
and a tightened ED threshold; or a range of ED thresholds spanning
between a most relaxed ED threshold and a most tightened ED
threshold.
4. The method of claim 3, further including: determining, by the
transmitter node, an access priority of the access trigger
condition, wherein the access priority indicates one of: a higher
priority access or a lower priority access; and selecting, by the
transmitter node, the ED threshold from the plurality of candidate
ED thresholds based on the access priority determined, wherein the
transmitter node selects the relaxed ED threshold when the access
priority corresponds to the higher priority access, and wherein the
transmitter node selects the tightened ED threshold when the access
priority corresponds to the lower priority access.
5. The method of claim 3, wherein the ED threshold is randomly
selected from the range of ED thresholds.
6. The method of claim 3, further including: failing, by the
transmitter node, to detect an access trigger condition, wherein
the ED threshold used in the performing the ED procedure includes
the standard ED threshold.
7. An apparatus configured for wireless communication, comprising:
means for identifying, by a transmitter node, information for
transmission on a shared communication channel; means for
identifying, by the transmitter node, for an access trigger
condition associated with access of the transmitter node to the
shared communication channel; means for performing, by the
transmitter node, an energy detection (ED) procedure for access to
the shared communication channel according to an ED threshold of a
plurality of candidate ED thresholds corresponding to the access
trigger condition; and means for transmitting, by the transmitter
node, the information on the shared communication channel in
response to success of the ED procedure.
8. The apparatus of claim 7, wherein the access trigger condition
includes one or more of: a traffic priority of the information; an
inability by the transmitter node to successfully access the shared
communication channel for at least a threshold period of time; a
threshold error rate detected by the transmitter node, wherein the
threshold error rate identifies errors that trigger modification of
a contention window size; and a deployment location, wherein the
deployment location indicates one of an indoor deployment or an
outdoor deployment.
9. The apparatus of claim 7, wherein the plurality of candidate ED
thresholds includes one of: one or more discrete ED thresholds
including at least a standard ED threshold, a relaxed ED threshold,
and a tightened ED threshold; or a range of ED thresholds spanning
between a most relaxed ED threshold and a most tightened ED
threshold.
10. The apparatus of claim 9, further including: means for
determining, by the transmitter node, an access priority of the
access trigger condition, wherein the access priority indicates one
of: a higher priority access or a lower priority access; and means
for selecting, by the transmitter node, the ED threshold from the
plurality of candidate ED thresholds based on the access priority
determined, wherein the transmitter node selects the relaxed ED
threshold when the access priority corresponds to the higher
priority access, and wherein the transmitter node selects the
tightened ED threshold when the access priority corresponds to the
lower priority access.
11. The apparatus of claim 9, wherein the ED threshold is randomly
selected from the range of ED thresholds.
12. The apparatus of claim 9, further including: means for failing,
by the transmitter node, to detect an access trigger condition,
wherein the ED threshold used in the performing the ED procedure
includes the standard ED threshold.
13. A non-transitory computer-readable medium having program code
recorded thereon, the program code comprising: program code
executable by a computer operable to cause the computer to
identify, by a transmitter node, information for transmission on a
shared communication channel; program code executable by the
computer operable to cause the computer to identify, by the
transmitter node, for an access trigger condition associated with
access of the transmitter node to the shared communication channel;
program code executable by the computer operable to cause the
computer to perform, by the transmitter node, an energy detection
(ED) procedure for access to the shared communication channel
according to an ED threshold of a plurality of candidate ED
thresholds corresponding to the access trigger condition; and
program code executable by the computer operable to cause the
computer to transmit, by the transmitter node, the information on
the shared communication channel in response to success of the ED
procedure.
14. The non-transitory computer-readable medium of claim 13,
wherein the access trigger condition includes one or more of: a
traffic priority of the information; an inability by the
transmitter node to successfully access the shared communication
channel for at least a threshold period of time; a threshold error
rate detected by the transmitter node, wherein the threshold error
rate identifies errors that trigger modification of a contention
window size; and a deployment location, wherein the deployment
location indicates one of an indoor deployment or an outdoor
deployment.
15. The non-transitory computer-readable medium of claim 13,
wherein the plurality of candidate ED thresholds includes one of:
one or more discrete ED thresholds including at least a standard ED
threshold, a relaxed ED threshold, and a tightened ED threshold; or
a range of ED thresholds spanning between a most relaxed ED
threshold and a most tightened ED threshold.
16. The non-transitory computer-readable medium of claim 15,
further including: program code executable by the computer operable
to cause the computer to determine, by the transmitter node, an
access priority of the access trigger condition, wherein the access
priority indicates one of: a higher priority access or a lower
priority access; and program code executable by the computer
operable to cause the computer to select, by the transmitter node,
the ED threshold from the plurality of candidate ED thresholds
based on the access priority determined, wherein the transmitter
node selects the relaxed ED threshold when the access priority
corresponds to the higher priority access, and wherein the
transmitter node selects the tightened ED threshold when the access
priority corresponds to the lower priority access.
17. The non-transitory computer-readable medium of claim 15,
wherein the ED threshold is randomly selected from the range of ED
thresholds.
18. The non-transitory computer-readable medium of claim 15,
further including: program code executable by the computer operable
to cause the computer to fail, by the transmitter node, to detect
an access trigger condition, wherein the ED threshold used in the
performing the ED procedure includes the standard ED threshold.
19. An apparatus configured for wireless communication, the
apparatus comprising: at least one processor; and a memory coupled
to the at least one processor, wherein the at least one processor
is configured: to identify, by a transmitter node, information for
transmission on a shared communication channel; to identify, by the
transmitter node, for an access trigger condition associated with
access of the transmitter node to the shared communication channel;
to perform, by the transmitter node, an energy detection (ED)
procedure for access to the shared communication channel according
to an ED threshold of a plurality of candidate ED thresholds
corresponding to the access trigger condition; and to transmit, by
the transmitter node, the information on the shared communication
channel in response to success of the ED procedure.
20. The apparatus of claim 19, wherein the access trigger condition
includes one or more of: a traffic priority of the information; an
inability by the transmitter node to successfully access the shared
communication channel for at least a threshold period of time; a
threshold error rate detected by the transmitter node, wherein the
threshold error rate identifies errors that trigger modification of
a contention window size; and a deployment location, wherein the
deployment location indicates one of an indoor deployment or an
outdoor deployment.
21. The apparatus of claim 20, wherein the plurality of candidate
ED thresholds includes one of: one or more discrete ED thresholds
including at least a standard ED threshold, a relaxed ED threshold,
and a tightened ED threshold; or a range of ED thresholds spanning
between a most relaxed ED threshold and a most tightened ED
threshold.
22. The apparatus of claim 21, further including configuration of
the at least one processor: to determine, by the transmitter node,
an access priority of the access trigger condition, wherein the
access priority indicates one of: a higher priority access or a
lower priority access; and to select, by the transmitter node, the
ED threshold from the plurality of candidate ED thresholds based on
the access priority determined, wherein the transmitter node
selects the relaxed ED threshold when the access priority
corresponds to the higher priority access, and wherein the
transmitter node selects the tightened ED threshold when the access
priority corresponds to the lower priority access.
23. The apparatus of claim 21, wherein the ED threshold is randomly
selected from the range of ED thresholds.
24. The apparatus of claim 21, further including configuration of
the at least one processor to fail, by the transmitter node, to
detect an access trigger condition, wherein the ED threshold used
in the performing the ED procedure includes the standard ED
threshold.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of U.S. Provisional
Patent Application No. 63/042,367, entitled, "ADAPTIVE ENERGY
DETECTION THRESHOLD MEDIUM ACCESS BASED ON DEPLOYMENT AND TRAFFIC
TYPE," filed on Jun. 22, 2020, which is expressly incorporated by
reference herein in its entirety.
BACKGROUND
Field
[0002] Aspects of the present disclosure relate generally to
wireless communication systems, and more particularly, to adaptive
energy detection (ED) threshold medium access based on deployment
and traffic type.
Background
[0003] Wireless communication networks are widely deployed to
provide various communication services such as voice, video, packet
data, messaging, broadcast, and the like. These wireless networks
may be multiple-access networks capable of supporting multiple
users by sharing the available network resources. Such networks,
which are usually multiple access networks, support communications
for multiple users by sharing the available network resources. One
example of such a network is the Universal Terrestrial Radio Access
Network (UTRAN). The UTRAN is the radio access network (RAN)
defined as a part of the Universal Mobile Telecommunications System
(UMTS), a third generation (3G) mobile phone technology supported
by the 3rd Generation Partnership Project (3GPP). Examples of
multiple-access network formats include Code Division Multiple
Access (CDMA) networks, Time Division Multiple Access (TDMA)
networks, Frequency Division Multiple Access (FDMA) networks,
Orthogonal FDMA (OFDMA) networks, and Single-Carrier FDMA (SC-FDMA)
networks.
[0004] A wireless communication network may include a number of
base stations or node Bs that can support communication for a
number of user equipments (UEs). A UE may communicate with a base
station via downlink and uplink. The downlink (or forward link)
refers to the communication link from the base station to the UE,
and the uplink (or reverse link) refers to the communication link
from the UE to the base station.
[0005] A base station may transmit data and control information on
the downlink to a UE and/or may receive data and control
information on the uplink from the UE. On the downlink, a
transmission from the base station may encounter interference due
to transmissions from neighbor base stations or from other wireless
radio frequency (RF) transmitters. On the uplink, a transmission
from the UE may encounter interference from uplink transmissions of
other UEs communicating with the neighbor base stations or from
other wireless RF transmitters. This interference may degrade
performance on both the downlink and uplink.
[0006] As the demand for mobile broadband access continues to
increase, the possibilities of interference and congested networks
grows with more UEs accessing the long-range wireless communication
networks and more short-range wireless systems being deployed in
communities. Research and development continue to advance wireless
technologies not only to meet the growing demand for mobile
broadband access, but to advance and enhance the user experience
with mobile communications.
SUMMARY
[0007] In one aspect of the disclosure, a method of wireless
communication includes identifying, by a transmitter node,
information for transmission on a shared communication channel,
identifying, by the transmitter node, for an access trigger
condition associated with access of the transmitter node to the
shared communication channel, performing, by the transmitter node,
an energy detection (ED) procedure for access to the shared
communication channel according to an ED threshold of a plurality
of candidate ED thresholds corresponding to the access trigger
condition, and transmitting, by the transmitter node, the
information on the shared communication channel in response to
success of the ED procedure.
[0008] In an additional aspect of the disclosure, an apparatus
configured for wireless communication includes means for
identifying, by a transmitter node, information for transmission on
a shared communication channel, means for identifying, by the
transmitter node, for an access trigger condition associated with
access of the transmitter node to the shared communication channel,
means for performing, by the transmitter node, an ED procedure for
access to the shared communication channel according to an ED
threshold of a plurality of candidate ED thresholds corresponding
to the access trigger condition, and means for transmitting, by the
transmitter node, the information on the shared communication
channel in response to success of the ED procedure.
[0009] In an additional aspect of the disclosure, a non-transitory
computer-readable medium having program code recorded thereon. The
program code further includes code to identify, by a transmitter
node, information for transmission on a shared communication
channel, code to identify, by the transmitter node, for an access
trigger condition associated with access of the transmitter node to
the shared communication channel, code to performing, by the
transmitter node, an ED procedure for access to the shared
communication channel according to an ED threshold of a plurality
of candidate ED thresholds corresponding to the access trigger
condition, and code to transmit, by the transmitter node, the
information on the shared communication channel in response to
success of the ED procedure.
[0010] In an additional aspect of the disclosure, an apparatus
configured for wireless communication is disclosed. The apparatus
includes at least one processor, and a memory coupled to the
processor. The processor is configured to identify, by a
transmitter node, information for transmission on a shared
communication channel, to identify, by the transmitter node, for an
access trigger condition associated with access of the transmitter
node to the shared communication channel, to performing, by the
transmitter node, an ED procedure for access to the shared
communication channel according to an ED threshold of a plurality
of candidate ED thresholds corresponding to the access trigger
condition, and to transmit, by the transmitter node, the
information on the shared communication channel in response to
success of the ED procedure.
[0011] The foregoing has outlined rather broadly the features and
technical advantages of examples according to the disclosure in
order that the detailed description that follows may be better
understood. Additional features and advantages will be described
hereinafter. The conception and specific examples disclosed may be
readily utilized as a basis for modifying or designing other
structures for carrying out the same purposes of the present
disclosure. Such equivalent constructions do not depart from the
scope of the appended claims. Characteristics of the concepts
disclosed herein, both their organization and method of operation,
together with associated advantages will be better understood from
the following description when considered in connection with the
accompanying figures. Each of the figures is provided for the
purpose of illustration and description, and not as a definition of
the limits of the claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] A further understanding of the nature and advantages of the
present disclosure may be realized by reference to the following
drawings. In the appended figures, similar components or features
may have the same reference label. Further, various components of
the same type may be distinguished by following the reference label
by a dash and a second label that distinguishes among the similar
components. If just the first reference label is used in the
specification, the description is applicable to any one of the
similar components having the same first reference label
irrespective of the second reference label.
[0013] FIG. 1 is a block diagram illustrating details of a wireless
communication system.
[0014] FIG. 2 is a block diagram illustrating a design of a base
station and a UE configured according to one aspect of the present
disclosure.
[0015] FIG. 3 is a block diagram illustrating a portion of a
wireless network having multiple coexisting RATs using a shared
communication spectrum.
[0016] FIG. 4 is a block diagram illustrating example blocks
executed to implement one aspect of the present disclosure.
[0017] FIG. 5 is a block diagram illustrating a portion of a
wireless network having multiple coexisting RATs using a shared
communication spectrum with a dynamic ED threshold framework
according to one aspect of the present disclosure.
[0018] FIG. 6 is a block diagram illustrating a portion of wireless
network 60 having multiple coexisting RATs using a shared
communication spectrum with a dynamic ED threshold framework
according to one aspect of the present disclosure.
[0019] FIG. 7 is a block diagram illustrating an example
configuration of a base station configured according to one aspect
of the present disclosure.
[0020] FIG. 8 is a block diagram illustrating an example
configuration of a UE configured according to one aspect of the
present disclosure.
DETAILED DESCRIPTION
[0021] The detailed description set forth below, in connection with
the appended drawings, is intended as a description of various
configurations and is not intended to limit the scope of the
disclosure. Rather, the detailed description includes specific
details for the purpose of providing a thorough understanding of
the inventive subject matter. It will be apparent to those skilled
in the art that these specific details are not required in every
case and that, in some instances, well-known structures and
components are shown in block diagram form for clarity of
presentation.
[0022] This disclosure relates generally to providing or
participating in authorized shared access between two or more
wireless communications systems, also referred to as wireless
communications networks. In various embodiments, the techniques and
apparatus may be used for wireless communication networks such as
code division multiple access (CDMA) networks, time division
multiple access (TDMA) networks, frequency division multiple access
(FDMA) networks, orthogonal FDMA (OFDMA) networks, single-carrier
FDMA (SC-FDMA) networks, LTE networks, GSM networks, 5.sup.th
Generation (5G) or new radio (NR) networks, as well as other
communications networks. As described herein, the terms "networks"
and "systems" may be used interchangeably.
[0023] An OFDMA network may implement a radio technology such as
evolved UTRA (E-UTRA), IEEE 802.11, IEEE 802.16, IEEE 802.20,
flash-OFDM and the like. UTRA, E-UTRA, and Global System for Mobile
Communications (GSM) are part of universal mobile telecommunication
system (UMTS). In particular, long term evolution (LTE) is a
release of UMTS that uses E-UTRA. UTRA, E-UTRA, GSM, UMTS and LTE
are described in documents provided from an organization named "3rd
Generation Partnership Project" (3GPP), and cdma2000 is described
in documents from an organization named "3rd Generation Partnership
Project 2" (3GPP2). These various radio technologies and standards
are known or are being developed. For example, the 3rd Generation
Partnership Project (3GPP) is a collaboration between groups of
telecommunications associations that aims to define a globally
applicable third generation (3G) mobile phone specification. 3GPP
long term evolution (LTE) is a 3GPP project which was aimed at
improving the universal mobile telecommunications system (UMTS)
mobile phone standard. The 3GPP may define specifications for the
next generation of mobile networks, mobile systems, and mobile
devices. The present disclosure is concerned with the evolution of
wireless technologies from LTE, 4G, 5G, NR, and beyond with shared
access to wireless spectrum between networks using a collection of
new and different radio access technologies or radio air
interfaces.
[0024] In particular, 5G networks contemplate diverse deployments,
diverse spectrum, and diverse services and devices that may be
implemented using an OFDM-based unified, air interface. In order to
achieve these goals, further enhancements to LTE and LTE-A are
considered in addition to development of the new radio technology
for 5G NR networks. The 5G NR will be capable of scaling to provide
coverage (1) to a massive Internet of things (IoTs) with an
ultra-high density (e.g., .about.1M nodes/km.sup.2), ultra-low
complexity (e.g., .about.10 s of bits/sec), ultra-low energy (e.g.,
.about.10+ years of battery life), and deep coverage with the
capability to reach challenging locations; (2) including
mission-critical control with strong security to safeguard
sensitive personal, financial, or classified information,
ultra-high reliability (e.g., .about.99.9999% reliability),
ultra-low latency (e.g., .about.1 ms), and users with wide ranges
of mobility or lack thereof; and (3) with enhanced mobile broadband
including extreme high capacity (e.g., .about.10 Tbps/km.sup.2),
extreme data rates (e.g., multi-Gbps rate, 100+ Mbps user
experienced rates), and deep awareness with advanced discovery and
optimizations.
[0025] The 5G NR may be implemented to use optimized OFDM-based
waveforms with scalable numerology and transmission time interval
(TTI); having a common, flexible framework to efficiently multiplex
services and features with a dynamic, low-latency time division
duplex (TDD)/frequency division duplex (FDD) design; and with
advanced wireless technologies, such as massive multiple input,
multiple output (MIMO), robust millimeter wave (mmWave)
transmissions, advanced channel coding, and device-centric
mobility. Scalability of the numerology in 5G NR, with scaling of
subcarrier spacing, may efficiently address operating diverse
services across diverse spectrum and diverse deployments. For
example, in various outdoor and macro coverage deployments of less
than 3GHz FDD/TDD implementations, subcarrier spacing may occur
with 15 kHz, for example over 1, 5, 10, 20 MHz, and the like
bandwidth. For other various outdoor and small cell coverage
deployments of TDD greater than 3 GHz, subcarrier spacing may occur
with 30 kHz over 80/100 MHz bandwidth. For other various indoor
wideband implementations, using a TDD over the unlicensed portion
of the 5 GHz band, the subcarrier spacing may occur with 60 kHz
over a 160 MHz bandwidth. Finally, for various deployments
transmitting with mmWave components at a TDD of 28 GHz, subcarrier
spacing may occur with 120 kHz over a 500 MHz bandwidth.
[0026] The scalable numerology of the 5G NR facilitates scalable
TTI for diverse latency and quality of service (QoS) requirements.
For example, shorter TTI may be used for low latency and high
reliability, while longer TTI may be used for higher spectral
efficiency. The efficient multiplexing of long and short TTIs to
allow transmissions to start on symbol boundaries. 5G NR also
contemplates a self-contained integrated subframe design with
uplink/downlink scheduling information, data, and acknowledgement
in the same subframe. The self-contained integrated subframe
supports communications in unlicensed or contention-based shared
spectrum, adaptive uplink/downlink that may be flexibly configured
on a per-cell basis to dynamically switch between uplink and
downlink to meet the current traffic needs.
[0027] Various other aspects and features of the disclosure are
further described below. It should be apparent that the teachings
herein may be embodied in a wide variety of forms and that any
specific structure, function, or both being disclosed herein is
merely representative and not limiting. Based on the teachings
herein one of an ordinary level of skill in the art should
appreciate that an aspect disclosed herein may be implemented
independently of any other aspects and that two or more of these
aspects may be combined in various ways. For example, an apparatus
may be implemented or a method may be practiced using any number of
the aspects set forth herein. In addition, such an apparatus may be
implemented or such a method may be practiced using other
structure, functionality, or structure and functionality in
addition to or other than one or more of the aspects set forth
herein. For example, a method may be implemented as part of a
system, device, apparatus, and/or as instructions stored on a
computer readable medium for execution on a processor or computer.
Furthermore, an aspect may comprise at least one element of a
claim.
[0028] FIG. 1 is a block diagram illustrating an example of a
wireless communications system 100 that supports adaptive or
dynamic energy detection (ED) threshold medium access based on
deployment and traffic type in accordance with aspects of the
present disclosure. The network nodes sharing a shared
communication network are configured with multiple discrete ED
thresholds or a range of ED values. As a transmitting node prepares
to attempt access to the shared communication spectrum, it
identifies an access trigger condition within the network. The
wireless communications system 100 includes base stations 105, UEs
115, and a core network 130. In some examples, the wireless
communications system 100 may be a Long Term Evolution (LTE)
network, an LTE-Advanced (LTE-A) network, an LTE-A Pro network, or
NR network. In some cases, wireless communications system 100 may
support enhanced broadband communications, ultra-reliable (e.g.,
mission critical) communications, low latency communications, or
communications with low-cost and low-complexity devices.
[0029] Base stations 105 may wirelessly communicate with UEs 115
via one or more base station antennas. Base stations 105 described
herein may include or may be referred to by those skilled in the
art as a base transceiver station, a radio base station, an access
point, a radio transceiver, a NodeB, an eNodeB (eNB), a
next-generation NodeB or giga-NodeB (either of which may be
referred to as a gNB), a Home NodeB, a Home eNodeB, or some other
suitable terminology. Wireless communications system 100 may
include base stations 105 of different types (e.g., macro or small
cell base stations). The UEs 115 described herein may be able to
communicate with various types of base stations 105 and network
equipment including macro eNBs, small cell eNBs, gNBs, relay base
stations, and the like.
[0030] Each base station 105 may be associated with a particular
geographic coverage area 110 in which communications with various
UEs 115 is supported. Each base station 105 may provide
communication coverage for a respective geographic coverage area
110 via communication links 125, and communication links 125
between a base station 105 and a UE 115 may utilize one or more
carriers. Communication links 125 shown in wireless communications
system 100 may include uplink transmissions from a UE 115 to a base
station 105, or downlink transmissions from a base station 105 to a
UE 115. Downlink transmissions may also be referred to as forward
link transmissions while uplink transmissions may also be referred
to as reverse link transmissions.
[0031] The geographic coverage area 110 for a base station 105 may
be divided into sectors making up a portion of the geographic
coverage area 110, and each sector may be associated with a cell.
For example, each base station 105 may provide communication
coverage for a macro cell, a small cell, a hot spot, or other types
of cells, or various combinations thereof. In some examples, a base
station 105 may be movable and, therefore, provide communication
coverage for a moving geographic coverage area 110. In some
examples, different geographic coverage areas 110 associated with
different technologies may overlap, and overlapping geographic
coverage areas 110 associated with different technologies may be
supported by the same base station 105 or by different base
stations 105. The wireless communications system 100 may include,
for example, a heterogeneous LTE/LTE-A/LTE-A Pro or NR network in
which different types of base stations 105 provide coverage for
various geographic coverage areas 110.
[0032] The term "cell" refers to a logical communication entity
used for communication with a base station 105 (e.g., over a
carrier), and may be associated with an identifier for
distinguishing neighboring cells (e.g., a physical cell identifier
(PCID), a virtual cell identifier (VCID)) operating via the same or
a different carrier. In some examples, a carrier may support
multiple cells, and different cells may be configured according to
different protocol types (e.g., machine-type communication (MTC),
narrowband Internet-of-things (NB-IoT), enhanced mobile broadband
(eMBB), or others) that may provide access for different types of
devices. In some cases, the term "cell" may refer to a portion of a
geographic coverage area 110 (e.g., a sector) over which the
logical entity operates.
[0033] UEs 115 may be dispersed throughout the wireless
communications system 100, and each UE 115 may be stationary or
mobile. A UE 115 may also be referred to as a mobile device, a
wireless device, a remote device, a handheld device, or a
subscriber device, or some other suitable terminology, where the
"device" may also be referred to as a unit, a station, a terminal,
or a client. A UE 115 may also be a personal electronic device such
as a cellular phone (UE 115a), a personal digital assistant (PDA),
a wearable device (UE 115d), a tablet computer, a laptop computer
(UE 115g), or a personal computer. In some examples, a UE 115 may
also refer to a wireless local loop (WLL) station, an
Internet-of-things (IoT) device, an Internet-of-everything (IoE)
device, an MTC device, or the like, which may be implemented in
various articles such as appliances, vehicles (UE 115e and UE
115f), meters (UE 115b and UE 115c), or the like.
[0034] Some UEs 115, such as MTC or IoT devices, may be low cost or
low complexity devices, and may provide for automated communication
between machines (e.g., via machine-to-machine (M2M)
communication). M2M communication or MTC may refer to data
communication technologies that allow devices to communicate with
one another or a base station 105 without human intervention. In
some examples, M2M communication or MTC may include communications
from devices that integrate sensors or meters to measure or capture
information and relay that information to a central server or
application program that can make use of the information or present
the information to humans interacting with the program or
application. Some UEs 115 may be designed to collect information or
enable automated behavior of machines. Examples of applications for
MTC devices include smart metering, inventory monitoring, water
level monitoring, equipment monitoring, healthcare monitoring,
wildlife monitoring, weather and geological event monitoring, fleet
management and tracking, remote security sensing, physical access
control, and transaction-based business charging.
[0035] Some UEs 115 may be configured to employ operating modes
that reduce power consumption, such as half-duplex communications
(e.g., a mode that supports one-way communication via transmission
or reception, but not transmission and reception simultaneously).
In some examples, half-duplex communications may be performed at a
reduced peak rate. Other power conservation techniques for UEs 115
include entering a power saving "deep sleep" mode when not engaging
in active communications, or operating over a limited bandwidth
(e.g., according to narrowband communications). In other cases, UEs
115 may be designed to support critical functions (e.g., mission
critical functions), and a wireless communications system 100 may
be configured to provide ultra-reliable communications for these
functions.
[0036] In certain cases, a UE 115 may also be able to communicate
directly with other UEs 115 (e.g., using a peer-to-peer (P2P) or
device-to-device (D2D) protocol). One or more of a group of UEs 115
utilizing D2D communications may be within the geographic coverage
area 110 of a base station 105. Other UEs 115 in such a group may
be outside the geographic coverage area 110 of a base station 105,
or be otherwise unable to receive transmissions from a base station
105. In some cases, groups of UEs 115 communicating via D2D
communications may utilize a one-to-many (1:M) system in which each
UE 115 transmits to every other UE 115 in the group. In some cases,
a base station 105 may facilitate the scheduling of resources for
D2D communications. In other cases, D2D communications may be
carried out between UEs 115 without the involvement of a base
station 105.
[0037] Base stations 105 may communicate with the core network 130
and with one another. For example, base stations 105 may interface
with the core network 130 through backhaul links 132 (e.g., via an
S1, N2, N3, or other interface). Base stations 105 may communicate
with one another over backhaul links 134 (e.g., via an X2, Xn, or
other interface) either directly (e.g., directly between base
stations 105) or indirectly (e.g., via core network 130).
[0038] The core network 130 may provide user authentication, access
authorization, tracking, Internet Protocol (IP) connectivity, and
other access, routing, or mobility functions. The core network 130
may be an evolved packet core (EPC), which may include at least one
mobility management entity (MME), at least one serving gateway
(S-GW), and at least one packet data network (PDN) gateway (P-GW).
The MME may manage non-access stratum (e.g., control plane)
functions such as mobility, authentication, and bearer management
for UEs 115 served by base stations 105 associated with the EPC.
User IP packets may be transferred through the S-GW, which itself
may be connected to the P-GW. The P-GW may provide IP address
allocation as well as other functions. The P-GW may be connected to
the network operators IP services. The operators IP services may
include access to the Internet, Intranet(s), an IP multimedia
subsystem (IMS), or a packet-switched (PS) streaming service.
[0039] At least some of the network devices, such as a base station
105, may include subcomponents such as an access network entity,
which may be an example of an access node controller (ANC). Each
access network entity may communicate with UEs 115 through a number
of other access network transmission entities, which may be
referred to as a radio head, a smart radio head, or a
transmission/reception point (TRP). In some configurations, various
functions of each access network entity or base station 105 may be
distributed across various network devices (e.g., radio heads and
access network controllers) or consolidated into a single network
device (e.g., a base station 105).
[0040] Wireless communications system 100 may operate using one or
more frequency bands, typically in the range of 300 megahertz (MHz)
to 300 gigahertz (GHz). Generally, the region from 300 MHz to 3 GHz
is known as the ultra-high frequency (UHF) region or decimeter
band, since the wavelengths range from approximately one decimeter
to one meter in length. UHF waves may be blocked or redirected by
buildings and environmental features. However, the waves may
penetrate structures sufficiently for a macro cell to provide
service to UEs 115 located indoors. Transmission of UHF waves may
be associated with smaller antennas and shorter range (e.g., less
than 100 km) compared to transmission using the smaller frequencies
and longer waves of the high frequency (HF) or very high frequency
(VHF) portion of the spectrum below 300 MHz.
[0041] Wireless communications system 100 may also operate in a
super high frequency (SHF) region using frequency bands from 3 GHz
to 30 GHz, also known as the centimeter band. The SHF region
includes bands such as the 5 GHz industrial, scientific, and
medical (ISM) bands, which may be used opportunistically by devices
that may be capable of tolerating interference from other
users.
[0042] Wireless communications system 100 may also operate in an
extremely high frequency (EHF) region of the spectrum (e.g., from
30 GHz to 300 GHz), also known as the millimeter band. In some
examples, wireless communications system 100 may support millimeter
wave (mmW) communications between UEs 115 and base stations 105,
and EHF antennas of the respective devices may be even smaller and
more closely spaced than UHF antennas. In some cases, this may
facilitate use of antenna arrays within a UE 115. However, the
propagation of EHF transmissions may be subject to even greater
atmospheric attenuation and shorter range than SHF or UHF
transmissions. Techniques disclosed herein may be employed across
transmissions that use one or more different frequency regions, and
designated use of bands across these frequency regions may differ
by country or regulating body.
[0043] Wireless communications system 100 may include operations by
different network operating entities (e.g., network operators), in
which each network operator may share spectrum. In some instances,
a network operating entity may be configured to use an entirety of
a designated shared spectrum for at least a period of time before
another network operating entity uses the entirety of the
designated shared spectrum for a different period of time. Thus, in
order to allow network operating entities use of the full
designated shared spectrum, and in order to mitigate interfering
communications between the different network operating entities,
certain resources (e.g., time) may be partitioned and allocated to
the different network operating entities for certain types of
communication.
[0044] For example, a network operating entity may be allocated
certain time resources reserved for exclusive communication by the
network operating entity using the entirety of the shared spectrum.
The network operating entity may also be allocated other time
resources where the entity is given priority over other network
operating entities to communicate using the shared spectrum. These
time resources, prioritized for use by the network operating
entity, may be utilized by other network operating entities on an
opportunistic basis if the prioritized network operating entity
does not utilize the resources. Additional time resources may be
allocated for any network operator to use on an opportunistic
basis.
[0045] Access to the shared spectrum and the arbitration of time
resources among different network operating entities may be
centrally controlled by a separate entity, autonomously determined
by a predefined arbitration scheme, or dynamically determined based
on interactions between wireless nodes of the network
operators.
[0046] In various implementations, wireless communications system
100 may use both licensed and unlicensed radio frequency spectrum
bands. For example, wireless communications system 100 may employ
license assisted access (LAA), LTE-unlicensed (LTE-U) radio access
technology, or NR technology in an unlicensed band (NR-U), such as
the 5 GHz ISM band. In some cases, UE 115 and base station 105 of
the wireless communications system 100 may operate in a shared
radio frequency spectrum band, which may include licensed or
unlicensed (e.g., contention-based) frequency spectrum. In an
unlicensed frequency portion of the shared radio frequency spectrum
band, UEs 115 or base stations 105 may traditionally perform a
medium-sensing procedure to contend for access to the frequency
spectrum. For example, UE 115 or base station 105 may perform a
listen before talk (LBT) procedure such as a clear channel
assessment (CCA) prior to communicating in order to determine
whether the shared channel is available.
[0047] A CCA may include an energy detection procedure to determine
whether there are any other active transmissions on the shared
channel. For example, a device may infer that a change in a
received signal strength indicator (RSSI) of a power meter
indicates that a channel is occupied. Specifically, signal power
that is concentrated in a certain bandwidth and exceeds a
predetermined noise floor may indicate another wireless
transmitter. A CCA also may include message detection of specific
sequences that indicate use of the channel. For example, another
device may transmit a specific preamble prior to transmitting a
data sequence. In some cases, an LBT procedure may include a
wireless node adjusting its own backoff window based on the amount
of energy detected on a channel and/or the
acknowledge/negative-acknowledge (ACK/NACK) feedback for its own
transmitted packets as a proxy for collisions.
[0048] In general, four categories of LBT procedure have been
suggested for sensing a shared channel for signals that may
indicate the channel is already occupied. In a first category (CAT
1 LBT), no LBT or CCA is applied to detect occupancy of the shared
channel. A second category (CAT 2 LBT), which may also be referred
to as an abbreviated LBT, a single-shot LBT, or a 25-.mu.s LBT,
provides for the node to perform a CCA to detect energy above a
predetermined threshold or detect a message or preamble occupying
the shared channel. The CAT 2 LBT performs the CCA without using a
random back-off operation, which results in its abbreviated length,
relative to the next categories.
[0049] A third category (CAT 3 LBT) performs CCA to detect energy
or messages on a shared channel, but also uses a random back-off
and fixed contention window. Therefore, when the node initiates the
CAT 3 LBT, it performs a first CCA to detect occupancy of the
shared channel. If the shared channel is idle for the duration of
the first CCA, the node may proceed to transmit. However, if the
first CCA detects a signal occupying the shared channel, the node
selects a random back-off based on the fixed contention window size
and performs an extended CCA. If the shared channel is detected to
be idle during the extended CCA and the random number has been
decremented to 0, then the node may begin transmission on the
shared channel. Otherwise, the node decrements the random number
and performs another extended CCA. The node would continue
performing extended CCA until the random number reaches 0. If the
random number reaches 0 without any of the extended CCAs detecting
channel occupancy, the node may then transmit on the shared
channel. If at any of the extended CCA, the node detects channel
occupancy, the node may re-select a new random back-off based on
the fixed contention window size to begin the countdown again.
[0050] A fourth category (CAT 4 LBT), which may also be referred to
as a full LBT procedure, performs the CCA with energy or message
detection using a random back-off and variable contention window
size. The sequence of CCA detection proceeds similarly to the
process of the CAT 3 LBT, except that the contention window size is
variable for the CAT 4 LBT procedure.
[0051] Use of a medium-sensing procedure to contend for access to
an unlicensed shared spectrum may result in communication
inefficiencies. This may be particularly evident when multiple
network operating entities (e.g., network operators) are attempting
to access a shared resource. In wireless communications system 100,
base stations 105 and UEs 115 may be operated by the same or
different network operating entities. In some examples, an
individual base station 105 or UE 115 may be operated by more than
one network operating entity. In other examples, each base station
105 and UE 115 may be operated by a single network operating
entity. Requiring each base station 105 and UE 115 of different
network operating entities to contend for shared resources may
result in increased signaling overhead and communication
latency.
[0052] In some cases, operations in unlicensed bands may be based
on a carrier aggregation configuration in conjunction with
component carriers operating in a licensed band (e.g., LAA).
Operations in unlicensed spectrum may include downlink
transmissions, uplink transmissions, peer-to-peer transmissions, or
a combination of these. Duplexing in unlicensed spectrum may be
based on frequency division duplexing (FDD), time division
duplexing (TDD), or a combination of both.
[0053] In some examples, base station 105 or UE 115 may be equipped
with multiple antennas, which may be used to employ techniques such
as transmit diversity, receive diversity, multiple-input
multiple-output (MIMO) communications, or beamforming. For example,
wireless communications system 100 may use a transmission scheme
between a transmitting device (e.g., a base station 105) and a
receiving device (e.g., a UE 115), where the transmitting device is
equipped with multiple antennas and the receiving device is
equipped with one or more antennas. MIMO communications may employ
multipath signal propagation to increase the spectral efficiency by
transmitting or receiving multiple signals via different spatial
layers, which may be referred to as spatial multiplexing. The
multiple signals may, for example, be transmitted by the
transmitting device via different antennas or different
combinations of antennas. Likewise, the multiple signals may be
received by the receiving device via different antennas or
different combinations of antennas. Each of the multiple signals
may be referred to as a separate spatial stream, and may carry bits
associated with the same data stream (e.g., the same codeword) or
different data streams. Different spatial layers may be associated
with different antenna ports used for channel measurement and
reporting. MIMO techniques include single-user MIMO (SU-MIMO) where
multiple spatial layers are transmitted to the same receiving
device, and multiple-user MIMO (MU-MIMO) where multiple spatial
layers are transmitted to multiple devices.
[0054] Beamforming, which may also be referred to as spatial
filtering, directional transmission, or directional reception, is a
signal processing technique that may be used at a transmitting
device or a receiving device (e.g., a base station 105 or a UE 115)
to shape or steer an antenna beam (e.g., a transmit beam or receive
beam) along a spatial path between the transmitting device and the
receiving device. Beamforming may be achieved by combining the
signals communicated via antenna elements of an antenna array such
that signals propagating at particular orientations with respect to
an antenna array experience constructive interference while others
experience destructive interference. The adjustment of signals
communicated via the antenna elements may include a transmitting
device or a receiving device applying certain amplitude and phase
offsets to signals carried via each of the antenna elements
associated with the device. The adjustments associated with each of
the antenna elements may be defined by a beamforming weight set
associated with a particular orientation (e.g., with respect to the
antenna array of the transmitting device or receiving device, or
with respect to some other orientation).
[0055] In one example, a base station 105 may use multiple antennas
or antenna arrays to conduct beamforming operations for directional
communications with a UE 115. For instance, some signals (e.g.
synchronization signals, reference signals, beam selection signals,
or other control signals) may be transmitted by a base station 105
multiple times in different directions, which may include a signal
being transmitted according to different beamforming weight sets
associated with different directions of transmission. Transmissions
in different beam directions may be used to identify (e.g., by the
base station 105 or a receiving device, such as a UE 115) a beam
direction for subsequent transmission and/or reception by the base
station 105.
[0056] Some signals, such as data signals associated with a
particular receiving device, may be transmitted by a base station
105 in a single beam direction (e.g., a direction associated with
the receiving device, such as a UE 115). In some examples, the beam
direction associated with transmissions along a single beam
direction may be determined based at least in in part on a signal
that was transmitted in different beam directions. For example, a
UE 115 may receive one or more of the signals transmitted by the
base station 105 in different directions, and the UE 115 may report
to the base station 105 an indication of the signal it received
with a highest signal quality, or an otherwise acceptable signal
quality. Although these techniques are described with reference to
signals transmitted in one or more directions by a base station
105, a UE 115 may employ similar techniques for transmitting
signals multiple times in different directions (e.g., for
identifying a beam direction for subsequent transmission or
reception by the UE 115), or transmitting a signal in a single
direction (e.g., for transmitting data to a receiving device).
[0057] A receiving device (e.g., a UE 115, which may be an example
of a mmW receiving device) may try multiple receive beams when
receiving various signals from the base station 105, such as
synchronization signals, reference signals, beam selection signals,
or other control signals. For example, a receiving device may try
multiple receive directions by receiving via different antenna
subarrays, by processing received signals according to different
antenna subarrays, by receiving according to different receive
beamforming weight sets applied to signals received at a plurality
of antenna elements of an antenna array, or by processing received
signals according to different receive beamforming weight sets
applied to signals received at a plurality of antenna elements of
an antenna array, any of which may be referred to as "listening"
according to different receive beams or receive directions. In some
examples a receiving device may use a single receive beam to
receive along a single beam direction (e.g., when receiving a data
signal). The single receive beam may be aligned in a beam direction
determined based at least in part on listening according to
different receive beam directions (e.g., a beam direction
determined to have a highest signal strength, highest
signal-to-noise ratio, or otherwise acceptable signal quality based
at least in part on listening according to multiple beam
directions).
[0058] In certain implementations, the antennas of a base station
105 or UE 115 may be located within one or more antenna arrays,
which may support MIMO operations, or transmit or receive
beamforming. For example, one or more base station antennas or
antenna arrays may be co-located at an antenna assembly, such as an
antenna tower. In some cases, antennas or antenna arrays associated
with a base station 105 may be located in diverse geographic
locations. A base station 105 may have an antenna array with a
number of rows and columns of antenna ports that the base station
105 may use to support beamforming of communications with a UE 115.
Likewise, a UE 115 may have one or more antenna arrays that may
support various MIMO or beamforming operations.
[0059] In additional cases, UEs 115 and base stations 105 may
support retransmissions of data to increase the likelihood that
data is received successfully. HARQ feedback is one technique of
increasing the likelihood that data is received correctly over a
communication link 125. HARQ may include a combination of error
detection (e.g., using a cyclic redundancy check (CRC)), forward
error correction (FEC), and retransmission (e.g., automatic repeat
request (ARQ)). HARQ may improve throughput at the MAC layer in
poor radio conditions (e.g., signal-to-noise conditions). In some
cases, a wireless device may support same-slot HARQ feedback, where
the device may provide HARQ feedback in a specific slot for data
received in a previous symbol in the slot, while in other cases,
the device may provide HARQ feedback in a subsequent slot, or
according to some other time interval.
[0060] Time intervals in LTE or NR may be expressed in multiples of
a basic time unit, which may, for example, refer to a sampling
period of T.sub.s=1/30,720,000 seconds. Time intervals of a
communications resource may be organized according to radio frames
each having a duration of 10 milliseconds (ms), where the frame
period may be expressed as T.sub.f=307,200 T.sub.s. The radio
frames may be identified by a system frame number (SFN) ranging
from 0 to 1023. Each frame may include 10 subframes numbered from 0
to 9, and each subframe may have a duration of 1 ms. A subframe may
be further divided into 2 slots each having a duration of 0.5 ms,
and each slot may contain 6 or 7 modulation symbol periods (e.g.,
depending on the length of the cyclic prefix prepended to each
symbol period). Excluding the cyclic prefix, each symbol period may
contain 2048 sampling periods. In some cases, a subframe may be the
smallest scheduling unit of the wireless communications system 100,
and may be referred to as a transmission time interval (TTI). In
other cases, a smallest scheduling unit of the wireless
communications system 100 may be shorter than a subframe or may be
dynamically selected (e.g., in bursts of shortened TTIs (sTTIs) or
in selected component carriers using sTTIs).
[0061] In some wireless communications systems, a slot may further
be divided into multiple mini-slots containing one or more symbols.
In some instances, a symbol of a mini-slot or a mini-slot may be
the smallest unit of scheduling. Each symbol may vary in duration
depending on the subcarrier spacing or frequency band of operation,
for example. Further, some wireless communications systems may
implement slot aggregation in which multiple slots or mini-slots
are aggregated together and used for communication between a UE 115
and a base station 105.
[0062] The term "carrier," as may be used herein, refers to a set
of radio frequency spectrum resources having a defined physical
layer structure for supporting communications over a communication
link 125. For example, a carrier of a communication link 125 may
include a portion of a radio frequency spectrum band that is
operated according to physical layer channels for a given radio
access technology. Each physical layer channel may carry user data,
control information, or other signaling. A carrier may be
associated with a pre-defined frequency channel (e.g., an evolved
universal mobile telecommunication system terrestrial radio access
(E-UTRA) absolute radio frequency channel number (EARFCN)), and may
be positioned according to a channel raster for discovery by UEs
115. Carriers may be downlink or uplink (e.g., in an FDD mode), or
be configured to carry downlink and uplink communications (e.g., in
a TDD mode). In some examples, signal waveforms transmitted over a
carrier may be made up of multiple sub-carriers (e.g., using
multi-carrier modulation (MCM) techniques such as orthogonal
frequency division multiplexing (OFDM) or discrete Fourier
transform spread OFDM (DFT-S-OFDM)).
[0063] The organizational structure of the carriers may be
different for different radio access technologies (e.g., LTE,
LTE-A, LTE-A Pro, NR). For example, communications over a carrier
may be organized according to TTIs or slots, each of which may
include user data as well as control information or signaling to
support decoding the user data. A carrier may also include
dedicated acquisition signaling (e.g., synchronization signals or
system information, etc.) and control signaling that coordinates
operation for the carrier. In some examples (e.g., in a carrier
aggregation configuration), a carrier may also have acquisition
signaling or control signaling that coordinates operations for
other carriers.
[0064] Physical channels may be multiplexed on a carrier according
to various techniques. A physical control channel and a physical
data channel may be multiplexed on a downlink carrier, for example,
using time division multiplexing (TDM) techniques, frequency
division multiplexing (FDM) techniques, or hybrid TDM-FDM
techniques. In some examples, control information transmitted in a
physical control channel may be distributed between different
control regions in a cascaded manner (e.g., between a common
control region or common search space and one or more UE-specific
control regions or UE-specific search spaces).
[0065] A carrier may be associated with a particular bandwidth of
the radio frequency spectrum, and in some examples the carrier
bandwidth may be referred to as a "system bandwidth" of the carrier
or the wireless communications system 100. For example, the carrier
bandwidth may be one of a number of predetermined bandwidths for
carriers of a particular radio access technology (e.g., 1.4, 3, 5,
10, 15, 20, 40, or 80 MHz). In some examples, each served UE 115
may be configured for operating over portions or all of the carrier
bandwidth. In other examples, some UEs 115 may be configured for
operation using a narrowband protocol type that is associated with
a predefined portion or range (e.g., set of subcarriers or RBs)
within a carrier (e.g., "in-band" deployment of a narrowband
protocol type).
[0066] In a system employing MCM techniques, a resource element may
consist of one symbol period (e.g., a duration of one modulation
symbol) and one subcarrier, where the symbol period and subcarrier
spacing are inversely related. The number of bits carried by each
resource element may depend on the modulation scheme (e.g., the
order of the modulation scheme). Thus, the more resource elements
that a UE 115 receives and the higher the order of the modulation
scheme, the higher the data rate may be for the UE 115. In MIMO
systems, a wireless communications resource may refer to a
combination of a radio frequency spectrum resource, a time
resource, and a spatial resource (e.g., spatial layers), and the
use of multiple spatial layers may further increase the data rate
for communications with a UE 115.
[0067] Devices of the wireless communications system 100 (e.g.,
base stations 105 or UEs 115) may have a hardware configuration
that supports communications over a particular carrier bandwidth,
or may be configurable to support communications over one of a set
of carrier bandwidths. In some examples, the wireless
communications system 100 may include base stations 105 and/or UEs
115 that support simultaneous communications via carriers
associated with more than one different carrier bandwidth.
[0068] Wireless communications system 100 may support communication
with a UE 115 on multiple cells or carriers, a feature which may be
referred to as carrier aggregation or multi-carrier operation. A UE
115 may be configured with multiple downlink component carriers and
one or more uplink component carriers according to a carrier
aggregation configuration. Carrier aggregation may be used with
both FDD and TDD component carriers.
[0069] In some cases, wireless communications system 100 may
utilize enhanced component carriers (eCCs). An eCC may be
characterized by one or more features including wider carrier or
frequency channel bandwidth, shorter symbol duration, shorter TTI
duration, or modified control channel configuration. In certain
instances, an eCC may be associated with a carrier aggregation
configuration or a dual connectivity configuration (e.g., when
multiple serving cells have a suboptimal or non-ideal backhaul
link). An eCC may also be configured for use in unlicensed spectrum
or shared spectrum (e.g., where more than one operator is allowed
to use the spectrum, such as NR-shared spectrum (NR-SS)). An eCC
characterized by wide carrier bandwidth may include one or more
segments that may be utilized by UEs 115 that are not capable of
monitoring the whole carrier bandwidth or are otherwise configured
to use a limited carrier bandwidth (e.g., to conserve power).
[0070] In additional cases, an eCC may utilize a different symbol
duration than other component carriers, which may include use of a
reduced symbol duration as compared with symbol durations of the
other component carriers. A shorter symbol duration may be
associated with increased spacing between adjacent subcarriers. A
device, such as a UE 115 or base station 105, utilizing eCCs may
transmit wideband signals (e.g., according to frequency channel or
carrier bandwidths of 20, 40, 60, 80 MHz, etc.) at reduced symbol
durations (e.g., 16.67 microseconds). A TTI in eCC may consist of
one or multiple symbol periods. In some cases, the TTI duration
(that is, the number of symbol periods in a TTI) may be
variable.
[0071] Wireless communications system 100 may be an NR system that
may utilize any combination of licensed, shared, and unlicensed
spectrum bands, among others. The flexibility of eCC symbol
duration and subcarrier spacing may allow for the use of eCC across
multiple spectrums. In some examples, NR shared spectrum may
increase spectrum utilization and spectral efficiency, specifically
through dynamic vertical (e.g., across the frequency domain) and
horizontal (e.g., across the time domain) sharing of resources.
[0072] FIG. 2 shows a block diagram of a design of a base station
105 and a UE 115, which may be one of the base station and one of
the UEs in FIG. 1. At base station 105, a transmit processor 220
may receive data from a data source 212 and control information
from a controller/processor 240. The control information may be for
the PBCH, PCFICH, PHICH, PDCCH, EPDCCH, MPDCCH etc. The data may be
for the PDSCH, etc. The transmit processor 220 may process (e.g.,
encode and symbol map) the data and control information to obtain
data symbols and control symbols, respectively. The transmit
processor 220 may also generate reference symbols, e.g., for the
PSS, SSS, and cell-specific reference signal. A transmit (TX)
multiple-input multiple-output (MIMO) processor 230 may perform
spatial processing (e.g., precoding) on the data symbols, the
control symbols, and/or the reference symbols, if applicable, and
may provide output symbol streams to the modulators (MODs) 232a
through 232t. Each modulator 232 may process a respective output
symbol stream (e.g., for OFDM, etc.) to obtain an output sample
stream. Each modulator 232 may further process (e.g., convert to
analog, amplify, filter, and upconvert) the output sample stream to
obtain a downlink signal. Downlink signals from modulators 232a
through 232t may be transmitted via the antennas 234a through 234t,
respectively.
[0073] At UE 115, the antennas 252a through 252r may receive the
downlink signals from the base station 105 and may provide received
signals to the demodulators (DEMODs) 254a through 254r,
respectively. Each demodulator 254 may condition (e.g., filter,
amplify, downconvert, and digitize) a respective received signal to
obtain input samples. Each demodulator 254 may further process the
input samples (e.g., for OFDM, etc.) to obtain received symbols. A
MIMO detector 256 may obtain received symbols from all the
demodulators 254a through 254r, perform MIMO detection on the
received symbols if applicable, and provide detected symbols. A
receive processor 258 may process (e.g., demodulate, deinterleave,
and decode) the detected symbols, provide decoded data for the UE
115 to a data sink 260, and provide decoded control information to
a controller/processor 280.
[0074] On the uplink, at the UE 115, a transmit processor 264 may
receive and process data (e.g., for the PUSCH) from a data source
262 and control information (e.g., for the PUCCH) from the
controller/processor 280. The transmit processor 264 may also
generate reference symbols for a reference signal. The symbols from
the transmit processor 264 may be precoded by a TX MIMO processor
266 if applicable, further processed by the modulators 254a through
254r (e.g., for SC-FDM, etc.), and transmitted to the base station
105. At the base station 105, the uplink signals from the UE 115
may be received by the antennas 234, processed by the demodulators
232, detected by a MIMO detector 236 if applicable, and further
processed by a receive processor 238 to obtain decoded data and
control information sent by the UE 115. The processor 238 may
provide the decoded data to a data sink 239 and the decoded control
information to the controller/processor 240.
[0075] The controllers/processors 240 and 280 may direct the
operation at the base station 105 and the UE 115, respectively. The
controller/processor 240 and/or other processors and modules at the
base station 105 may perform or direct the execution of various
processes for the techniques described herein. The
controllers/processor 280 and/or other processors and modules at
the UE 115 may also perform or direct the execution of the
functional blocks illustrated in FIG. 4, and/or other processes for
the techniques described herein. The memories 242 and 282 may store
data and program codes for the base station 105 and the UE 115,
respectively. A scheduler 244 may schedule UEs for data
transmission on the downlink and/or uplink.
[0076] FIG. 3 is a block diagram illustrating a portion of wireless
network 30 having multiple coexisting RATs using a shared
communication spectrum. The illustrated portion of wireless network
30 includes NR-U nodes, UE 115a and 115h and base station 105a,
which coexists with a WiFi network via WiFi nodes, UE 115i and base
station 105b. Base station 105b may also serve NR-U nodes in a
license assisted access (LAA) implementation. For example, UE 115j
may communicate over licensed spectrum as the anchor carrier with
base station 105a and unlicensed NR-U spectrum for a secondary
carrier via base station 105b. Each of UEs 115a, 115h, 115i, and
115j also include technology-specific access deferrals. NR-U
operations define media access through transmitter sensing. For
example, energy detection (ED) has been suggested for the
transmitter sensing at a threshold level suitable for unlicensed
spectrum. In some proposed implementations, an ED threshold of -72
dBm has been indicated to be suitable for accessing such unlicensed
spectrum by NR-U nodes, such as UEs 115a and 115h and base station
105a and for UE 115j for accessing the unlicensed spectrum at base
station 105b.
[0077] NR-U networks, such as deployed within wireless network 30,
may coexist on the same shared communication spectrum with multiple
different radio access technologies (RATs), which may have various
different access procedures and deferrals, including different ED
thresholds or additional ED thresholds for additional access
procedures or deferrals. For example, in addition to a medium
access ED threshold, WiFi medium access procedures also may rely on
a receiver protection procedure through preamble detection and
request-to-send (RTS)/clear-to-send (CTS) signaling. Because WiFi
nodes, such as UE 115i and base station 105b, additionally defer
medium access based on a preamble detection ED threshold at -82
dBm, suggestions have been put forth to increase the access ED
threshold for WiFi nodes to -62 dBm.
[0078] Different ED thresholds among different technologies can
potentially lead to fairness issues in the case of NR-U and WiFi
coexistence, which may favor WiFi access over NR-U access. It has
been suggested that all RATs accessing a shared communication
spectrum should use the same access ED threshold. However, using
the same access ED threshold among different technologies can
itself lead to fairness issues in the case of NR-U and WiFi
coexistence, which may favor NR-U access over WiFi access.
Accordingly, the various aspects of the present disclosure are
directed to a dynamic ED threshold that may be determined based on
an access trigger condition, such as traffic priority, delayed
access, error detection, or even geographic considerations, such as
indoor location versus outdoor location.
[0079] FIG. 4 is a block diagram illustrating example blocks
executed to implement one aspect of the present disclosure. The
example blocks will also be described with respect to base station
105 as illustrated in FIGS. 2 and 7. FIG. 7 is a block diagram
illustrating base station 105 configured according to one aspect of
the present disclosure. Base station 105 includes the structure,
hardware, and components as illustrated for base station 105 of
FIG. 2. For example, base station 105 includes controller/processor
240, which operates to execute logic or computer instructions
stored in memory 242, as well as controlling the components of base
station 105 that provide the features and functionality of base
station 105. Base station 105, under control of
controller/processor 240, transmits and receives signals via
wireless radios 700a-t and antennas 234a-t. Wireless radios 700a-t
includes various components and hardware, as illustrated in FIG. 2
for base station 105, including modulator/demodulators 232a-t, MIMO
detector 236, receive processor 238, transmit processor 220, and TX
MIMO processor 230.
[0080] The example blocks will also be described with respect to UE
115 as illustrated in FIGS. 2 and 8. FIG. 8 is a block diagram
illustrating UE 115 configured according to one aspect of the
present disclosure. UE 115 includes the structure, hardware, and
components as illustrated for UE 115 of FIG. 2. For example, UE 115
includes controller/processor 280, which operates to execute logic
or computer instructions stored in memory 282, as well as
controlling the components of UE 115 that provide the features and
functionality of UE 115. UE 115, under control of
controller/processor 280, transmits and receives signals via
wireless radios 800a-r and antennas 252a-r. Wireless radios 800a-r
includes various components and hardware, as illustrated in FIG. 2
for UE 115, including modulator/demodulators 254a-r, MIMO detector
256, receive processor 258, transmit processor 264, and TX MIMO
processor 266.
[0081] At block 400, a transmitter node identifies information for
transmission on a shared communication channel. When the
transmitter node is implemented as a base station, such as base
station 105, base station 105 may identify either control signaling
or data stored in memory 242, at data buffer 701 that are available
for downlink transmissions.
[0082] When the transmitter node is implemented as a UE, such as UE
115, UE 115 may further identify either reference signals or uplink
data in memory 282 at data buffer 801.
[0083] At block 401, the transmitter node identifies an access
trigger condition associated with access of the transmitter node to
the shared communication channel. When the transmitter node is
implemented as base station 105, base station 105, under control of
controller/processor 240, executes adaptive ED procedure logic 702,
stored in memory 242. The additional functionality available to
base station 105 that is enabled through the execution of the
instructions and logic of adaptive ED procedure logic 702 provides
base station 105 with a set of access trigger conditions to
identify. Each different access trigger condition may trigger base
station 105 to perform an ED procedure for access to the shared
communication channel using a particular ED threshold associated
with that particular trigger condition. Base station 105 would then
identify such access trigger conditions as they occur.
[0084] When the transmitter node is implemented as UE 115, UE 115,
under control of controller/processor 280, also would execute
adaptive ED procedure logic 802, stored in memory 282. The
additional functionality available to UE 115 that is enabled
through the execution of the instructions and logic of adaptive ED
procedure logic 802 provides UE 115 with a set of access trigger
conditions to identify. Each different access trigger condition may
trigger UE 115 to perform an ED procedure for access to the shared
communication channel using a ED threshold associated corresponding
to that particular trigger condition. UE 115 would then identify
such access trigger conditions as they occur.
[0085] At block 402, the transmitter node performs an ED procedure
for access to the shared communication channel according to an ED
threshold of a plurality of candidate ED thresholds corresponding
to the access trigger condition. When the transmitter node is
implemented as base station 105, within the execution environment
of adaptive ED procedure logic 702, base station 105, under control
of controller/processor 240, selects the corresponding ED threshold
value in memory 242 at set of candidate ED thresholds 703. Base
station 105 performs the ED procedure for accessing the shared
communication channel using the selected ED threshold associated
with the access trigger condition.
[0086] When the transmitter node is implemented as UE 115, within
the execution environment of adaptive ED procedure logic 802, UE
115, further under control of controller/processor 280, selects the
corresponding ED threshold value in memory 282 at set of candidate
ED thresholds 803. UE 115 performs the ED procedure for accessing
the shared communication channel using the selected ED threshold
associated with the access trigger condition.
[0087] At block 403, the transmitter node transmits the information
on the shared communication channel in response to success of the
ED procedure. When the transmitter node is implemented as base
station 105, once base station 105 successfully obtains access to
the shared communication channel after the ED procedure, base
station 105 will transmit the data or control signaling via
wireless radios 700a-t and antennas 234a-t.
[0088] When the transmitter node is implemented as UE 115, once UE
115 successfully obtains access to the shared communication channel
after the ED procedure, UE 115 will transmit the data or control
signaling via wireless radios 800a-r and antennas 252a-r.
[0089] FIG. 5 is a block diagram illustrating a portion of wireless
network 50 having multiple coexisting RATs using a shared
communication spectrum with a dynamic ED threshold framework
according to one aspect of the present disclosure. Current
RAT-specific standards generally set a single ED threshold
regardless of access condition allowing, instead, a different
contention window size or channel occupancy time (COT) to address
different traffic priority classes. In the dynamic ED threshold
framework according to the various aspects described herein, each
network node of all RATs sharing the shared communication spectrum
of wireless network 30 may be configured with a set of candidate ED
thresholds.
[0090] In one example aspect, the dynamic ED threshold framework
configures all RATs sharing access to the shared spectrum with
multiple discrete ED thresholds. A first such discrete ED threshold
reflects a standard ED threshold used by the transmitting node to
access the medium under standard conditions (e.g., -N dBm {-70 dBm,
-72 dBm, -74 dBm, etc.}). Such standard ED threshold may be common
to all transmitting nodes of each RAT for neutral or standard
access conditions. A second discrete ED threshold may reflect a
relaxed threshold for higher priority traffic or traffic configured
with a preference over other traffic. For example, UE 115h may be
preparing for ultra-reliability, low-latency communications (URLLC)
transmission, which carries a higher traffic priority. Upon
detecting this access trigger condition, the transmitting node, UE
115h, may trigger dynamically relaxing the ED threshold. UE 115h
would then select the relaxed ED threshold, -X dBm, within the set
of candidate ED thresholds (e.g., -X dBm {-60 dBm, -62 dBm, -64
dBm, etc. }).
[0091] A third discrete ED threshold may reflect a heightened or
strengthened threshold for lower priority traffic or traffic
configured with a lower preference relative to other traffic.
According to the aspects described herein, where the access trigger
condition reflects a lower priority traffic, the transmitting node,
according to the example aspects, may tighten or strengthen the ED
threshold by selecting the heightened ED threshold, -Y dBm (e.g.,
-Y dBm {-80 dBm, -82 dBm, -84 dBm, etc. }). For example, UE 115a
may be preparing for transmission at a low-priority traffic class.
In such case, UE 115a identifies the access trigger condition of
low priority traffic and selects the strengthened ED threshold, -Y
dBm, for attempting access to the shared medium. Thus, according
one example aspect of the illustrated example, the transmitting
nodes of wireless network 30 may each be configured with a set of
multiple candidate ED thresholds (e.g., -X dBm, -N dBm, -Y dBm).
The transmitting node may dynamically select which candidate ED
threshold to use based on the observed or detected access trigger
condition.
[0092] It should be noted that, in the case of the LAA traffic,
such as between UE 115j and base station 105b, such traffic may
also qualify as lower priority traffic and, thus, trigger selection
by UE 115j of the strengthened ED threshold, -Y dBm.
[0093] Another optional aspect illustrated in FIG. 5 defines the
set of candidate ED thresholds to a range or distribution or even a
mean value of available ED thresholds. Thus, instead of a single
value, e.g., ED=-N dBm, or set of discrete values, e.g., ED=-X dBm,
-N dBm, -Y dBm, a range, distribution, or mean value is specified.
For example, ED threshold=range[-Y dBm, -X dBm] or range[-82 dBm,
-62 dBm], or with a mean value of ED threshold=-L dBm, where -L dBm
may or may not be equal to -(X+Y)/2 dBm. The transmitting node in
wireless network 30 may select to implement a random ED threshold
from the set of candidate ED thresholds. Therefore, based on the
access trigger condition, the transmitting node, such as any of UEs
115a, 115h, 115i, 115j, or base stations 105a or 105b, may select
to use a random ED threshold from the identified range.
[0094] According to additional aspects of the present disclosure,
as illustrated in FIG. 5, the access trigger condition for
selecting from the set of candidate ED thresholds may include other
conditions associated with the node's previous access or access
attempts to the share medium. In one example aspect, a transmitting
node, such as UE 115a, may have been attempting to access the
shared communication spectrum for a predetermined period of time.
When UE 115a determines that it has not been able to successfully
access the shared spectrum for the predetermined period of time, it
may select a relaxed ED threshold from the set of candidate ED
thresholds. In such example aspect, the relaxed ED threshold may
increase the likelihood that UE 115a may successfully access the
shared spectrum.
[0095] The access trigger condition may further relate to current
channel conditions that effect the error rate of the node's
previous transmissions. For example, if UE 115h has successfully
obtained access to the shared medium for transmission, but the
error rate for such transmissions exceeded a threshold error rate,
UE 115h may select a strengthened ED threshold from the set of
candidate ED thresholds. The strengthened ED threshold may result
in an decreased error rate on subsequent transmission by backing
off when interfering signals are detected at the strengthened ED
threshold that may not have been detected at the ED threshold
previously used by UE 115h. Such an example aspect may further
relate to the allowed COT size. Where the allowed COT size is below
a certain length, UE 115h may select the strengthened ED threshold.
The access trigger condition for tightening the ED threshold could
be detection of errors that also affect contention window size
adaption.
[0096] FIG. 6 is a block diagram illustrating a portion of wireless
network 60 having multiple coexisting RATs using a shared
communication spectrum with a dynamic ED threshold framework
according to one aspect of the present disclosure. Wireless network
60 includes a base station 105a that facilitates an NR-U network
serving NR-U compatible UEs, such as UEs 115a, 115h, and
potentially UEs 115i and 115j. Base station 105b is a multiple RAT
base station that includes support for WiFi, Bluetooth, and NR-U
communications. UEs 115i and 115j are located inside of structure
600 and identified as indoors. UEs 115a and 115h are each located
outside of structure 600 and identified as outdoors. The selected
ED threshold used by the transmitting nodes in wireless network 60
may be semi-statically selected based on detection deployment of
the particular node. For example, indoor deployments, such as UEs
115i and 115j and base station 105b, may select a higher energy
threshold value (e.g., a relaxed ED threshold, -X dBm) as the
coexistence requirements for such indoor nodes may not be as strict
because the owner of structure 600 can control access to who
deploys at base station 105b. Conversely, the outdoor deployments,
such as UEs 115a and 115h and base station 105a, may select a lower
energy threshold value (e.g., a strengthened ED threshold, -Y dBm)
as the coexistence requirements may be more stringent, because
multiple "operators" may deploy a network covering the same
geographical area.
[0097] In operation, UEs 115i and 115j may semi-statically select a
relaxed ED threshold, -X dBm, from the set of candidate ED
thresholds upon detecting the access trigger condition identifying
UEs 115i and 115j as indoors. UEs 115a and 115h semi-statically
select a strengthened ED threshold, -Y dBm, from the set of
candidate ED thresholds upon detecting the access trigger condition
identifying UEs 115a and 115h as outdoors. UEs 115i and 115j each
use the relaxed ED threshold, -X dBm, for accessing the shared
communication spectrum via base station 105b, via ED procedures 601
and 602. If the owner of structure 600 does not wholly excluded any
UEs not identified as within structure 600 from accessing base
station 105b, UEs 115a and 115h could attempt to access the shared
communication spectrum via base station 105b via ED procedures 603
and 604. When each of UEs 115a, 115h, 115i, and 115j attempt to
access the shared spectrum via base station 105b, one of the indoor
UEs, UEs 115i and 115j, may likely successfully achieve access to
the detriment of UEs 115a and 115h, as the indoor nodes use the
more relaxed ED threshold, while the outdoor nodes use the
strengthened ED threshold. If the outdoor UEs, UEs 115a and 115h
fail to access the shared spectrum via base station 105b, they may
fall back to attempting access via base station 105a using ED
procedures 605 and 606.
[0098] Those of skill in the art would understand that information
and signals may be represented using any of a variety of different
technologies and techniques. For example, data, instructions,
commands, information, signals, bits, symbols, and chips that may
be referenced throughout the above description may be represented
by voltages, currents, electromagnetic waves, magnetic fields or
particles, optical fields or particles, or any combination
thereof.
[0099] The functional blocks and modules in FIG. 4 may comprise
processors, electronics devices, hardware devices, electronics
components, logical circuits, memories, software codes, firmware
codes, etc., or any combination thereof.
[0100] Those of skill would further appreciate that the various
illustrative logical blocks, modules, circuits, and algorithm steps
described in connection with the disclosure herein may be
implemented as electronic hardware, computer software, or
combinations of both. To clearly illustrate this interchangeability
of hardware and software, various illustrative components, blocks,
modules, circuits, and steps have been described above generally in
terms of their functionality. Whether such functionality is
implemented as hardware or software depends upon the particular
application and design constraints imposed on the overall system.
Skilled artisans may implement the described functionality in
varying ways for each particular application, but such
implementation decisions should not be interpreted as causing a
departure from the scope of the present disclosure. Skilled
artisans will also readily recognize that the order or combination
of components, methods, or interactions that are described herein
are merely examples and that the components, methods, or
interactions of the various aspects of the present disclosure may
be combined or performed in ways other than those illustrated and
described herein.
[0101] The various aspects of the present disclosure may be
implemented in many different ways, including methods, processes,
non-transitory computer-readable medium having program code
recorded thereon, apparatus having one or more processors with
configurations and instructions for performing the described
features and functionality, and the like. A first example aspect
configured for wireless communication includes identifying, by a
transmitter node, information for transmission on a shared
communication channel, identifying, by the transmitter node, for an
access trigger condition associated with access of the transmitter
node to the shared communication channel, performing, by the
transmitter node, an ED procedure for access to the shared
communication channel according to an ED threshold of a plurality
of candidate ED thresholds corresponding to the access trigger
condition, and transmitting, by the transmitter node, the
information on the shared communication channel in response to
success of the ED procedure.
[0102] A second aspect, alone or in combination with the first
aspect, wherein the access trigger condition includes one or more
of a traffic priority of the information; an inability by the
transmitter node to successfully access the shared communication
channel for at least a threshold period of time; a threshold error
rate detected by the transmitter node, wherein the threshold error
rate identifies errors that trigger modification of a contention
window size; and a deployment location, wherein the deployment
location indicates one of an indoor deployment or an outdoor
deployment.
[0103] A third aspect, alone or in combination with the first
aspect, wherein the plurality of candidate ED thresholds includes
one of one or more discrete ED thresholds including at least a
standard ED threshold, a relaxed ED threshold, and a tightened ED
threshold; or a range of ED thresholds spanning between a most
relaxed ED threshold and a most tightened ED threshold.
[0104] A fourth aspect, alone or in combination with the third
aspect, further including determining, by the transmitter node, an
access priority of the access trigger condition, wherein the access
priority indicates one of: a higher priority access or a lower
priority access; and selecting, by the transmitter node, the ED
threshold from the plurality of candidate ED thresholds based on
the determined access priority, wherein the transmitter node
selects the relaxed ED threshold when the access priority
corresponds to the higher priority access, and wherein the
transmitter node selects the tightened ED threshold when the access
priority corresponds to the lower priority access.
[0105] A fifth aspect, alone or in combination with the third
aspect, wherein the ED threshold is randomly selected from the
range of ED thresholds.
[0106] A sixth aspect, alone or in combination with the third
aspect, further including failing, by the transmitter node, to
detect an access trigger condition, wherein the ED threshold used
in the performing the ED procedure includes the standard ED
threshold.
[0107] A seventh aspect including any combination of the first
aspect through the sixth aspect.
[0108] The various illustrative logical blocks, modules, and
circuits described in connection with the disclosure herein may be
implemented or performed with a general-purpose processor, a
digital signal processor (DSP), an application specific integrated
circuit (ASIC), a field programmable gate array (FPGA) or other
programmable logic device, discrete gate or transistor logic,
discrete hardware components, or any combination thereof designed
to perform the functions described herein. A general-purpose
processor may be a microprocessor, but in the alternative, the
processor may be any conventional processor, controller,
microcontroller, or state machine. A processor may also be
implemented as a combination of computing devices, e.g., a
combination of a DSP and a microprocessor, a plurality of
microprocessors, one or more microprocessors in conjunction with a
DSP core, or any other such configuration.
[0109] The steps of a method or algorithm described in connection
with the disclosure herein may be embodied directly in hardware, in
a software module executed by a processor, or in a combination of
the two. A software module may reside in RAM memory, flash memory,
ROM memory, EPROM memory, EEPROM memory, registers, hard disk, a
removable disk, a CD-ROM, or any other form of storage medium known
in the art. An exemplary storage medium is coupled to the processor
such that the processor can read information from, and write
information to, the storage medium. In the alternative, the storage
medium may be integral to the processor. The processor and the
storage medium may reside in an ASIC. The ASIC may reside in a user
terminal. In the alternative, the processor and the storage medium
may reside as discrete components in a user terminal.
[0110] In one or more exemplary designs, the functions described
may be implemented in hardware, software, firmware, or any
combination thereof. If implemented in software, the functions may
be stored on or transmitted over as one or more instructions or
code on a computer-readable medium. Computer-readable media
includes both computer storage media and communication media
including any medium that facilitates transfer of a computer
program from one place to another. Computer-readable storage media
may be any available media that can be accessed by a general
purpose or special purpose computer. By way of example, and not
limitation, such computer-readable media can comprise RAM, ROM,
EEPROM, CD-ROM or other optical disk storage, magnetic disk storage
or other magnetic storage devices, or any other medium that can be
used to carry or store desired program code means in the form of
instructions or data structures and that can be accessed by a
general-purpose or special-purpose computer, or a general-purpose
or special-purpose processor. Also, a connection may be properly
termed a computer-readable medium. For example, if the software is
transmitted from a website, server, or other remote source using a
coaxial cable, fiber optic cable, twisted pair, or digital
subscriber line (DSL), then the coaxial cable, fiber optic cable,
twisted pair, or DSL, are included in the definition of medium.
Disk and disc, as used herein, includes compact disc (CD), laser
disc, optical disc, digital versatile disc (DVD), floppy disk and
blu-ray disc where disks usually reproduce data magnetically, while
discs reproduce data optically with lasers. Combinations of the
above should also be included within the scope of computer-readable
media.
[0111] As used herein, including in the claims, the term "and/or,"
when used in a list of two or more items, means that any one of the
listed items can be employed by itself, or any combination of two
or more of the listed items can be employed. For example, if a
composition is described as containing components A, B, and/or C,
the composition can contain A alone; B alone; C alone; A and B in
combination; A and C in combination; B and C in combination; or A,
B, and C in combination. Also, as used herein, including in the
claims, "or" as used in a list of items prefaced by "at least one
of" indicates a disjunctive list such that, for example, a list of
"at least one of A, B, or C" means A or B or C or AB or AC or BC or
ABC (i.e., A and B and C) or any of these in any combination
thereof.
[0112] The previous description of the disclosure is provided to
enable any person skilled in the art to make or use the disclosure.
Various modifications to the disclosure will be readily apparent to
those skilled in the art, and the generic principles defined herein
may be applied to other variations without departing from the
spirit or scope of the disclosure. Thus, the disclosure is not
intended to be limited to the examples and designs described herein
but is to be accorded the widest scope consistent with the
principles and novel features disclosed herein.
* * * * *